The present invention relates to implements for attachment to mobile work vehicles and, more particularly, to a tree shear attachment having particular utility as a substitute for the digging bucket on a backhoe so as to provide a shear having a remarkably high degree of maneuverability and range of motion.
Various tree shear attachments are presently available for skid steer and front end loaders and tractors to permit an operator to remove brush and small trees along roadsides and other areas. However, for the most part, such attachments are designed for mounting on three point hitches or front end lift arms associated with such vehicles, thus limiting their range of motion. Moreover, many current commercially available shears have reliability problems and do not provide satisfactory means for safely and securely handling severed portions of the tree during the shearing action and immediately thereafter.
The present invention provides a tree shear attachment having particular, but not exclusive, utility as a substitute for the bucket of a backhoe so that an extremely broad range of motion is obtained for the shear, allowing it to be cocked and manipulated into a multitude of different positions most suited for handling the shearing job confronting the operator. A sturdy base frame of the shear is attached to the outer end of the boom assembly of the backhoe and can be rocked back and tipped forward through an extensive arc about a transverse axis to most advantageously position shearing jaws projecting forwardly from the frame, while the extendable nature of the boom assembly and its articulated design, as well as its ability to swing from side-to-side, contribute to extreme flexibility in terms of positioning and operating the shear. The shearing jaws lie in a horizontal plane that is offset below the transverse plane of the pivot axis of the shear so that the jaws can be brought down very close to the ground at the base of the tree to leave a minimal stump, such offset also facilitating further positioning and trimming of the tree once it has been felled.
In a preferred embodiment, the shear utilizes one fixed jaw and one moveable jaw, the fixed jaw being provided with a forwardly extending anvil while the moveable jaw has a sturdy shear blade that is brought into shearing engagement with an anvil during operation. At the front ends of the jaws, special retainers grip and hold the butt end of the tree following severance to assist in stabilizing and controlling the severed portion. Additionally, an overhead stabilizing rack mounted on the base frame has a pair of laterally spaced, forwardly extending stabilizing arms overlying the respective jaws to confine and stabilize the severed tree. The arm above the stationary jaw has an inturned forward portion so as to present a generally concave receiving nook that faces and is opposed to the moveable jaw. During severance, the moving jaw tends to push the upper extremities of the tree into the nook where it is cradled by the inturned arm. The other stabilizing arm is preferably straight but is provided with a laterally inwardly extending projection at its forwardmost end that helps engage and stabilize limbs of the severed tree. Preferably, the hydraulic operating cylinder for the moveable jaw is housed within a protective housing that shields the cylinder from damage during operation and use.